The invention relates to a blowout valve assembly, i.e. a so-called blowout preventer (BOP), with a connecting channel which can be closed by at least one closing device, whereby the closing device can be transversally displaced with regard to the connecting channel by means of a drive device.
Such a blowout valve assembly is used both with terrestrial and maritime mineral oil or natural gas drilling wells. The blowout valve assembly is used to prevent an uncontrolled blowout of the mineral oil or natural gas which is conveyed under high pressure along the pipe lines. To achieve this, the blowout valve assembly comprises at least one closing device. A connecting channel of the blowout valve assembly is arranged in the pipe line, whereby the conveyed mineral oil or natural gas also passes through this connecting channel. The closing device can be transversally displaced with regard to the connecting channel and is displaced if necessary by a drive device so far in the direction of the connecting channel that it is closed and an uncontrolled blowout of mineral oil or natural gas is prevented.
With the blowout valve assembly known in practice the drive device operates hydraulically. Consequently, the blowout valve assembly must have available an appropriate pipe system for the supply of the hydraulic fluid, and appropriate hydraulic devices for operating this blowout valve assembly, more of these arrangements or also more devices for mineral oil and natural gas supply must be arranged outside of the blowout valve assembly. The drive device is therefore quite complicated.
A further disadvantage in this connection is that whereas a large force can be applied by a hydraulic drive device, it cannot be controlled precisely. It can therefore arise that the closing device either does not shut off sufficiently tightly or shuts off too tightly so that it can hardly be opened again. In addition, a slow and partial opening of the closing device is not always possible with a hydraulic drive device.